Californian rancher Nathan Carver squints as he surveys the parched fields where his family has raised cattle for five generations.

Normally, they would be covered in lush green grass. But the western US state's worst drought in decades has reduced the land to a moonscape, leaving the 55-year-old father-of-four praying for rain.

"My grandparents tell of the Dust Bowl years in the late 30s when it was very bad and dry with dust storms blowing. But this is as bad as we have ever seen it in my lifetime," he told AFP.

Governor Jerry Brown last month declared a state of emergency due to what could be the worst drought in a century for California including its ultra-fertile Central Valley.

With no significant rain since November, state authorities identified 17 communities it warned could run out of water within 60-120 days, if the drought continues.

Only last Friday, California's State Water Project announced for the first time in its 54-year history that it cannot deliver anything beyond the bare minimum to maintain public health and safety.

For small family herdsman like Carver, the drought means no grass for their cattle to graze on.

The only options are buying hay at inflated prices -- 20 to 30 percent above usual because of demand -- or selling their cows.

"If the drought continues, we'll have to take desperate measures," Carver warned.

Drought means cattle sell-off

"Many of the ranchers are selling out. Because at some point, if you don't have the grass, you can't afford to buy the hay to feed the cows any more," he said at his ranch near Bakersfield.

Indeed, business appeared brisk at the weekly cattle auction in nearby Famoso, where buyers looked on from tiered benches as animals were led in for sale, the auctioneer shouting out fast-changing bids.

Justin Mebane, owner-manager of the Western Stockman's Market, said more cattle are being put up for sale, but things could get even busier.

"This is just the tip of the iceberg," he told the local Bakersfield Californian newspaper. "If we don't get some rain ... ranchers will need to liquidate their herds."

Jack Lavers, who is on the executive committee of California Cattlemen's Association (CCA), told AFP that cattle markets like the one in Famoso would typically be handling 200 to 300 cattle a day.

"They're getting over 1,000 head a day right now. That's every sale yard up and down the state," said Lavers, who has already cut his 400-head herd by a third, and plans to sell another 10 to 20 percent in the next couple of months.

"It's phenomenal. Guys are just selling cattle as fast as they can, trying to save what feed they have or ... completely selling out. ..It's been bad for the last couple of years, but this year has really been the worst."

California's drought -- the third winter in a row with well below average rainfall -- has also extended the annual wildfire season through into the winter, including one just outside Los Angeles that forced thousands of residents to evacuate.

The western state's rivers and reservoirs have hit record lows, with only 20 percent of the normal average supplies of water from melting snowpack, which flows down from the Sierra Nevada.

Back on his ranch, Carver can see the foothills of the Sierra away to the east. Every spring he drives his 250-strong herd up onto more fertile higher pastures, before bringing them down to warmer temperatures in the winter.

Before the Gold Rush

One of his forefathers first began raising cattle here in 1837, when the land was still the Wild West, even before the Gold Rush. So the drought threat is a tough slog.

Despite the current crisis, the herdsman is determined that the family business will pass to one of his four children -- three sons and a daughter -- when he retires.

"This drought is very difficult to survive, not just in the physical and monetary sense, of buying hay and feeding the crows and all the work that goes with that. It's also very difficult on the mental and emotional side.

"Every day I have to come out here and feed the cows and look at this dry brown ground and it can be depressing and discouraging."

But he vowed to fight on, helped by the wisdom and knowledge handed down by "our family, our generations of family that have gone before us .. and our faith in God.

"Our hope for rain, that's what keeps ranchers in business," he said, adding: "Ranchers are eternal optimists. We always are hoping for a better year next year."